From: Eric Luo <eric.wenbl@...>
Date: 2006-01-20T11:09:37+09:00
Subject: Re: Question about regular expression

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Sorry for my mistake.

I do want to let "STR bla SNPB" matched. but I said it mistakenly in the
opposite in my lastest post.

I want that the appearance of the word rather string STR just before a SNPB
will cause the match to fail.

That is, "STR bla SNPB", "PreSTR SNPB" "STRSNPB" will be matched.
but "STR SNPB" will not.




2006/1/20, ara.t.howard@noaa.gov <ara.t.howard@noaa.gov>:
>
> On Thu, 19 Jan 2006, Eric Luo wrote:
>
> > In your solution:
> >
> >  <SNPB>  <foo SNPB>  <SNPB bar>  <foo SNPB bar> matched.
> >
> > But "STR bla SNPB " will also be matched, which is not expected.
>
> it should not:
>
>    irb(main):002:0> %r/^ (?: (?:[^S]) | (?:S[^T]) | (?:ST[^R]) )* SNPB
> /ox.match "STR bla SNPB "
>    =3D> nil
>
> and does not on any of my machines.  are you seeing something different?
>
>
>
> the way that regular expression reads is:
>
>    - beginning of line
>
>    - zero or more things that are either
>      - not an S
>      - an S followed by not a T
>      - or ST followed by not an R
>
>    - the string SNPB
>
>    (we ignore the remainder of the string, though you could do more here
> if
>    needed)
>
> so the appearance of the string STR __anywhere__ before a SNPB will cause
> the
> match to fail.
>
> hth.
>
> -a
> --
> strong and healthy, who thinks of sickness until it strikes like
> lightning?
> preoccupied with the world, who thinks of death, until it arrives like
> thunder?  -- milarepa
>
>
>

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